الفهرس 
ِAcknowledgementOnly 14 pages are availabe for public view
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Abstract
Nowadays, generation of new materials, (polymer nanocomposites- PNCs) through inorganic nanoparticles uniform distribution in the polymer matrix has become very popular as it offers several advantages in industrial communities. Due to the large surface area of the nanoparticles, clay has been often used for preparation of polymer nanocomposites (PNCs). Polymer/clay nanocomposites, formed by dispersing nanosized clay particles in a polymer matrix, have received much attention in both scientific and industrial fields.
Study of molecular motion of polymers at the interfacial area between the matrix polymer and the clay is important for an understanding of the improved properties of nanocomposites. To detect changes in molecular dynamics in polymers, glass transition and dynamic glass transition are studied.
The polymer used through out this article from the semi-crystalline polymers (polyamide (PA6)) Filled with clay (Nanofil 919) as well as various concentrations to provide a wide range of systems with different mobility. Besides the pure polymers, a polymer inorganic nano-composite was chosen to be working materials to compare the dynamic behavior of the immobilized amorphous fraction (RAF) and relaxation behavior in semicrystalline polymers and polymer inorganic nano¬composites using different techniques as calorimetric technique
(Two kinds of calorimetry were used, which are (DSC), and (TMDSC) techniques), beside these techniques Dielectric Spectroscopy (DRS) and Dynamic Mechanical Analysis (DMA) techniques were used.
Using analyzing heat capacity of (PA6) semi crystalline nanocomposites, two different parts of RAF can be detected. One due to the interface between nanoparticle and polymer and the other due to the interface between crystallites and amorphous polymer and also we found a slight decrease of Tg following the addition of 29.2 wt.% of nanoparticles, Whereas for composites with less than 29.2 wt.% nanoparticles, the Tg is independent on filler content. The remaining mobile amorphous fraction in fully crystallized semicrystalline nanocomposites is nearly independent on filler content.
DRS measurements show there, in agreement with other techniques, that the cooperative a process is suppressed in the nanocomposites, as compared to pure polyamidc, whereas activity increases in the region of the secondary relaxations, dc conductivity dominates the dielectric loss e” at low frequencies /higher temperatures but at high frequency (10 Hz) this effect becomes very small and one can easy determine the dielectric Tg value for PA6 matrix which is about 45-50°C and this value is agreement with that in DSC measurements. Also an overall increase of (e1) with temperature at low frequencies and a
structure (step) at 1- 103 Hz are observed for all samples (which depends on clay loading).
Using both the time-temperature superposition principle and Vogel-Fulcher-Tammann-Hesse (VFTH) equation for Dynamic measurements one could calculate the relaxation time from which we also deduce the fragility parameter. The calculation of the fragility parameter indicates the tendency of PA6 to be stronger glass former upon the addition of the clay filler. from the dynamic mechanical measurements, no filler dependence (< 13.3wt %) of the mobile amorphous fraction could be seen from DMA and DSC measurements.